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Post by johnjsgems on Oct 19, 2012 20:46:13 GMT -5
I thought so but my mind got fuzzy.
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zarguy
fully equipped rock polisher
Cedar City, Utah - rockhound heaven!
Member since December 2005
Posts: 1,791
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Post by zarguy on Oct 20, 2012 22:48:48 GMT -5
China Park. I like that name.
Lynn
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boxofrocks
off to a rocking start
Member since July 2011
Posts: 1
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Post by boxofrocks on Dec 31, 2012 10:06:16 GMT -5
Denny - I have one and use it all the time. It's great for doing flats. Dust is the only problem. It doesn't have a fitting for a vacume hookup. It's a little scarry when you first turn it on high speed. It dims the lights in my shop until it gets up to speed. It turns about 2000 rpm's on high. The belts and disks are a little spendy. Very few places have them. I love it.
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sheltie
freely admits to licking rocks
Member since January 2012
Posts: 982
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Post by sheltie on Dec 31, 2012 11:04:42 GMT -5
Hey Dean!
Welcome aboard "over here". This group isn't nearly as "gritty" as we are but they are also very helpful and more oriented toward what happens after the houndin' part than we are. Belonging to these two forums really helps to fill in the blanks, so to speak.
Denny
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RockIt2Me
has rocks in the head
Sometimes I have to tell myself, "It's not worth the jail time."
Member since December 2009
Posts: 668
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Post by RockIt2Me on Dec 31, 2012 13:30:51 GMT -5
Lookee, I built a mini-Bull Wheel---->
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sheltie
freely admits to licking rocks
Member since January 2012
Posts: 982
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Post by sheltie on Dec 31, 2012 13:55:28 GMT -5
Very clever! I've always admired those who the aptitude to "do" things. I just play golf. ;D
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Post by mohs on Jan 2, 2013 23:59:09 GMT -5
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mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on Feb 19, 2013 19:37:41 GMT -5
sheltie, You NEED a bull wheel. For several reasons.
I have polished maybe a couple thousand slabs on mine. I sell my stuff summers in Montana, which is one of the principle reasons a picked a bull wheel. Everything else is painfully slow compared to a bull wheel, even an 8 x 3. If you have a lot of stuff to crank out, it doesn't take long for the tool to pay for itself.
Secondly, it works dry only- no water, slop, cleanup. Wear a respirator, hearing protection (a must) and thick gloves. This thing loves human flesh.
There are no diamond belts available. Heck, nobody could afford them anyway, plus like I said the machine is only made to run dry.
The key point to success with a bull wheel is to have a flat slab to start with. I have a dedicated 27" HP vibrating lap that I only run 220 in, for the sole purpose of grinding the slabs flat. Back up a step. The key to not having to leave a slab on the lap for two weeks is to start with a good diamond blade. I recommend an MK301 or 303. These blades are manufactured in Korea, using state of the art equipment, and are superior to anything that was ever manufactured in the US. Do not, do not, do not try to save money and buy a cheap Chinese blade.
I run the rock thru 100,220,400, and 600 grit belts on the bull wheel. Then back to a separate vibrating lap for polish.
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mikeinsjc
spending too much on rocks
Member since June 2010
Posts: 329
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Post by mikeinsjc on Feb 20, 2013 1:48:33 GMT -5
A continuation on my earlier post. A few things I have learned on the bull wheel;
The bull wheel takes some getting used to, and can be a bit discouraging at first. The biggest mistakes one usually makes with a bull wheel are using too much pressure on the rock, and not sanding the surface uniformly. As I use a vibrating lap for final polish, I must be careful not to dish the rock trying to get scratches out. The 100 grit is the most important step. In five seconds of sanding it becomes obvious if the rock will sand out or if it needs to go back to the grinding lap. My rule is if I can see saw blade marks, I stop sanding. If the marks are deep, I break it up and tumble the pieces. This is only because time is critical for me- if you are just doing stuff for grins, one can take as much time as they need.
Don't discard your belts too soon. A belt that feels smooth to your hand may still have a lot of life in it. You can tell when a belt is done- it simply ceases to remove scratches from the previous step. Don't get rid of it early.
I buy belts 10 at a time in each grit from Kingsley-North. I average one to two 5 gallon buckets of slabs per belt before it gives out.
Another tip if you are doing slabs: even though they make belts down to 36 grit for the bull wheel, you will find you are creating a lot of work for yourself if you start with anything less than 100 grit or 80 grit. You will play heck getting the scratches out a 36 grit belt leaves.
It is best to examine the rock in sunlight after each step. Diffuse light makes the rocks look better than they really are. Rotate the rock 90 degrees between each belt grit. It makes the sanding marks you have to remove more apparent, and it is easier to gauge your progress.
Here's an important tip: the belts on an expanding drum do not automatically center themselves when it turns on. This is particularly important to watch on a bull wheel because of the high speeds involved (sand on the fastest speed ). If the belt wobbles, it transfers chatter marks onto the rock which are very difficult to remove. To prevent this, hold the shaft of a screwdriver or chisel next to the belt/drum when you first turn it on. This aligns the edge of the belt with the side of the drum. Makes a huge difference.
As I mentioned earlier, don't neglect to wear gloves, thinking "I'll just touch up this one piece". Wounds in which the skin is erased down to the blood vessels take a long time to heal, and there is no machine that does it better than this one.
The bull wheel fills a niche and what it is meant to do it does well, and quickly. I need lots of slabs processed quickly. and haven't discovered any machine that does it better, and I will put my final polished slabs up against anyone's.
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Post by johnjsgems on Feb 20, 2013 11:13:26 GMT -5
Dry sanding finishes rock fast but a good respirator should be worn. Not a $2 dust mask. Adequate ventilation is also good.
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